Obscured by Clouds. The rough and ready blog of a cloud benighted biologist and amateur astronomer. Astroblog will cover my interests in astronomy, biology and Life, the Universe and Everything.

Thursday, October 08, 2015

Occultation of Venus, morning Friday October 9, 2015

Early morning sky on Friday October 9 looking east as seen from
Adelaide
at 4:55 ACDST showing the crescent Moon and Venus, just as Venus is about to disappear behind the Moon.
The inset shows the telescopic view of Venus at this time. Click to embiggen

Early morning sky on Friday October 9 looking east as seen from Melbourne
at 5:35 AEDST showing the crescent Moon and Venus, just as Venus is about to disappear behind the Moon.
The inset shows the telescopic view of Venus at this time. Click to embiggen

Early morning sky on Friday October 9 looking east as seen from Brisbane
at 4:21 AEST showing the crescent Moon and Venus, just as Venus is about to disappear behind the Moon.
The inset shows the telescopic view of Venus at this time. Click to embiggen

Early morning sky on Friday October 9 looking east as seen from
Adelaide
at 6:10 ACDST showing the crescent Moon and Venus, just as Venus has reappeared from behind the Moon.
The inset shows the telescopic view of Venus at this time. Click to embiggen

Early morning sky on Friday October 9 looking east as seen from Melbourne
at 6:50 AEDST showing the crescent Moon and Venus, just as Venus has reappeared from behind the Moon.
The inset shows the telescopic view of Venus at this time. Click to embiggen

Early morning sky on Friday October 9 looking east as seen from Brisbane
at 5:47 AEST showing the crescent Moon and Venus, just as Venus has reappeared from behind the Moon.
The inset shows the telescopic view of Venus at this time. Click to embiggen

On the early morning of October the 9th crescent Venus is occulted by the
crescent Moon as seen from central and eastern Australia, with eastern
Australia having the best view of the disappearance. Central Australia sees Venus reappear in the twilight, while for most of the east coast Venus reappears after sunrise.

The occultation occurs with the Moon low above the
horizon at the start for the eastern states, and very low or just below
the horizon for the central states. For example from Alice Springs Venus is below
the horizon when the occultation starts, and Venus emerges from behind
the Moon at 5:44 am ACDST. This is very close to the horizon. Venus
disappears behind the bright edge of the Moon, which is easily visible
and a ready signpost to Venus.

While the occultation is easily visible to the unaided eye, the sight in even a small telescope of the "half-Moon" Venus
disappearing behind crescent Moon will be rather awesome. It is
advisable to set up and practise on the Moon a day or so before the
event, so you are familiar with your telescope set-up. Set up at least
half an hour ahead of time so that you can be sure everything is
working well and you can watch the entire event comfortably (trying to
focus your telescope on Venus moments before the occultation will cause a
lot of unnecessary stress). Venus will be clearly visible to the
unaided eye near the Moon.

Venus reappears from behind the Moon after sunrise in the eastern
states, and in bright twilight in the central states. Despite this,
Venus will be readily observable. You may have to make sure your scope
is tracking on the dark side of the Moon before it is lost in the
twilight though.

Timings in Universal Time for a number of cities is here. The table below shows the occultation times for selected cites at the various local times.

Place

Moon rise

Disappears Bright Limb

Reappears Dark Limb

Astronomical Twilight

Sunrise

Adelaide ACDST

4:35

4:55

6:08

5:14

6:41

Brisbane AEST

2:59

4:21

5:47

3:59

5:18

Canberra AEDST

4:22

5:32

6:53

5:01

6:28

Darwin ACST

3:49

-

5:10

5:14

6:25

Hobart AEDST

4:38

5:49

6:59

4:51

6:30

Melbourne AEDST

4:42

5:35

6:50

5:13

6:43

Perth AWST

3:35

-

-

4:20

5:44

Sydney AEDST

4:12

5:31

6:54

4:56

6:21

As well, Adelaideians will be treated to a bright pass of the international space station at 5:40 am ACDTS above the crescent Moon and Venus (In Melbourne the ISS passes over at 6:15 AEDST, and in Brisbane at 3:38 AEST).

During the occultation, Mars and Jupiter rise to form a line with the Moon.
After the occultation is over it is possible to see Venus in the daylight using the crescent Moon as a guide (if you are careful to avoid the Sun).